I am looking for an alternative to the water I am presently using (well water with high levels of iron and sulfur). Carbon filtering does not remove enough of these elements. I have access to RO (reverse osmosis) water at work. I know that RO water is stripped of all minerals. Is there a formula for adding minerals back into RO water?

Swany,
Try using / purchasing Spring Water from the store. Stay clear of the Distilled Water it has nutrients that have been remove that the yeast need to do their job effectively. It will work but, you will get a better outcome with Spring Water.

If you're making all-grain beer, you'll need around 100 ppm Calcium and a balance between Calcium Chloride and Calcium Carbonate to fit the target SRM of the beer in order to have the correct mash pH. For more detailed information, read chapter 15 of John Palmer's How to Brew. You should own the book if you're serious about brewing, but you can read the chapter online at howtobrew.com

I usually match water to style...like Burton on Trent for a Pale Ale, London for a Sweet Stout, Vienna for a Lager, etc. So here's what I do: I use RO water that I buy from our local grocery which is ion-free and costs $.25 per gallon. Typically I will use 8 gallons for a 5 gallon batch. I use Beer Tools which has a water calculator in it. You can add the ions you need to match the style of beer you are making. It will calculate the ions per gallon and give you a total ion addition for the gallons you'll need.

In some cases I use our tap water here which in this example...a small amount of Epsom Salts and Chalk are added to match Vienna's water. Good for lagers and Oktoberfests. If your tap water is loaded with Iron and Sulphur I agree that you should not use it.

Anyway, the Beer Tools calculators are great for getting the beer to taste right. Most of your brew is water and the recipes have been developed to work with the water that was available resulting in a style of beer. You may not get an "exact" match on water additions, but close is attainable and your beer will benefit.

Once you get used to doing it you will also be able to vary these additions to taste and get even better results. The same goes for grains, hops and yeast...once you learn what you like in a given beer you will be able to tweak it to taste.